(1) Field of the Invention
The present invention relates to a process for the preparation of an olefin polymer, more particularly to a process for the preparation of an olefin polymer wherein the polymerization activity of the catalyst is high, and lowers less with time, and the stereoregularity of the obtained olefin polymer is high.
(2) Description of the Related Art
Hitherto, a process for the preparation of an olefin polymer was known which used a Ziegler-Natta catalyst comprising a combination of a carrier obtained by partially halogenating a dialkoxymagnesium and a solid catalyst component carrying a titanium component (Japanese Patent Publication No. 25441/1985).
However, regarding the above-mentioned catalyst, although the polymerization activity per unit time is high initially, the polymerization activity per unit time lowers greatly with the lapse of time of the polymerization. Therefore, in the case wherein it is required to prolong the time of the polymerization as in the case of a block copolymerization reaction, it is not advantageous to use the above-mentioned catalyst in view of the production of an olefin polymer.
The object of the present invention is to provide a process for the preparation of an olefin polymer wherein the above defect of the prior art is overcome, the polymerization activity lowers less with time, the stereoregularity of the obtained olefin polymer is high, and the catalyst residue remained in said olefin polymer is less.